Isotope separating apparatus



n 1955 R. c. VAN SICKLE 2,712,076

ISOTOPE SEPARATING APPARATUS Filed June 12, 1946 2 Shets-Sheet 1 INVENTOR.

YZarweZi 6: Va Jz'ckle 51 q, 1,, BY

J1me 1955 R. c. VAN SICKLE ISOTOFE SEPARATING APPARATUS 2 Sheets-Sheet 2 Filed June 12, 1946 V INVENTOR. $012M??? C. Z/a'n fickie rsorore sErAnAriNo APPARATUS Rosweli C. Van Sickle, Fittshurgh, Pa, assignor, by mesne assignments, to the United States of America as represented by the United dtates Atomic Energy Commission Application June 12, 1346, Serial No. 676,221

(Q1. 25ll--41.9)

10 Galois.

This invention is concerned with improvements in isotope separating apparatus and particularly involves improved arrangements for maintaining the ion source in such apparatus in operative condition.

in known types of apparatus used for separating the isotapes of a material, for example in the type of apparatus i' itggi States "fitfi G the volatilizsd material emerges or is emitted during ionization thereof. During operation the elongated opening or slit 1 become fouled up or otherwise contaminated with condensate of the material or other contaminants and since the geometry of the slit in relation to other parts is critical, it is imperative that the slit or opening be kept clean, that is, free of contaminating material. The object of my invention is to provide improved means for cleaning this slit in isotope separating apparatus of the type referred to for the purpose of maintaining it in a proper and eflicient operating condition.

Another object of my invention is to provide a slit cleaning mechanism for ion sources of the type referred to above embodying a straight line motion producing mechanism for causing the slit cleaning element to move in a straight line in the slit or elongated opening without the presence of bulky or unwieldly guide members or other mechanisms in the immediate vicinity of the elongated opening of the ion source.

Another object of my invention is to provide a slit cleaning device embodying an operating mechanism so arranged that the cleaning element can be operated by means of a push rod or plunger movable in a direction at right angles to the plane of movement of the slit cleaning element.

Another object of my invention is to provide a slit cleaner mechanism for a plurality of ion sources comprising a single operating mechanism arranged to produce a straight line motion and attached to a plurality of slit cleaning elements.

Further objects of my invention and numerous of its advantages will become apparent from the following detailed description and annexed drawing wherein Fig. 1 is a diagrammatic cross-sectional view of an isotope separating apparatus embodying an ion source with the slit cleaning mechanism of my invention associated therewith.

Fi g. 2 is a diagrammatic sectional view taken along the line 2-2 of Fig. 1 showing the relationship of the magnetic field producing means to the chamber within which is the isotope separating apparatus.

Fig. 3 is a diagrammatic perspective view of the slit cleaning mechanism with the parts rotated to the right substantially through 90 from the position in which they are shown in Fig. 1, and with some of the parts partly broken away.

lit)

Zfilidid The apparatus of Fig. 1 is of the type disclosed in greater detail in the prior application referred to above. The apparatus of Pig. 1 includes a tank it the interior of which is evacuated to a relatively high degree of vacuum as will presently be described. The tank it) is shown in cross section, and one side is closed by a relatively heavy face plate 11 which is attached to the tank by means of screw clamps i2 and 13, there being provided suitable bearing surfaces on the face plate 11 and on the tank it so that when the face plate 11 is clamped in position it engages the tank in sealing relationship so as to insure against loss of vacuum at the joint. All of the mechanism of the tank It is attached to and carried by the face plate 11 as will presently be explained.

The tank It has windows 1 15, 16 and 17 so as to make it possible to watch operations within the tank and there is a large discharge outlet 2% through which the air and moisture in the tank are evacuatedv The discharge outlet 26 is connected to a diffusion pump or pumps 21 by a pipe 22 and the diffusion pump is connected to a mechanical pump or pumps 23 by a pipe 24. The mechanical pump 23 may be a Kinney pump, for example, which is a rotary type of pump. In practice a liquid nitrogen trap may be used in the tank 10 for freezing out moisture or it may be associated with the pipe 22 connected to the ditlusion pump. Also, a trap using solidified carbon dioxide may be used in association with the pipe 24 for freezing out moisture from the air before it reaches the pump 23.

The tank it is disposed between laminated iron cores or pole pieces 27 as shown in cross section in Fig. 2 and surrounding these pole pieces are electrical windings 25, the windings being disposed within tanks or housings 29, one of the housings 29 being shown in Pig. 1. The

" windings 28 are energized with electrical current so that a relatively intense magnetic field is produced which is in a direction transverse to the tank 1%, that is, in a horizontal direction looking at Fig. 2 and in a direction perpendicular to the paper looking at Fig. 1. A cooling medium such as cooled oil or the like is circulated through the housings 2.9 for the purpose of cooling the coils therein.

Within the tank 10 is a liner structure 35 in the form of an arcuate conduit which forms a passageway for a beam or beams of ions generated at the lower end of the liner and received in a receiver or collector at the upper end of the liner. The liner 35 and the apparatus associated therewith are carried by the face plate 11 by means of a supporting structure designated by the numerals 36 and 37 and the brace member 38. The liner itself is attached to and spaced from the supporting structure by insulators 31a, 32, and 33 since, as will presently be disclosed, the linear is maintained at a different potential than the supporting structure. Within the lower right corner of tank Hi there are a pair of castings 4d and 40' which form containers within which the material to be ionized is vaporized. The castings 40 and iii may be supported from the supporting structure 36. The castings 40 and 4t), and the apparatus associated with each are identical so that thedescription of one applies to the other as well.

The casting 40 comprises a lower portion 31 and a smaller upper portion 52, the upper portion being con nected by a converging throat as shown. Within the portion 31 is a container or bottle 43 which is removable and in which the charge material itself is placed, that is, the charge of material to be ionized. Numeral 52 designates an electrical heating element or heating elements associated with container 49 which supply heat for volatilizing the charge material within the bottle 43. In the side wall of the smaller portion 42 of casting 40 there is a well 53 and the casting 40 has a similar well 53'. Electrical controls are provided for electrically controlling the supply of power for energizing the heating elements 52 and 52. The electrical controls for heating element 52' as shown are responsive to a thermocouple which is placed in the well 53' and the controls may preferably include the control known as the Micromax manufactured by the Leeds & Northrup Company; this control is designated by the numeral 54' and the thermocouple in well 53' is connected to it. The instrument 54 is connected to a control instrument 55 which is a type of instrument which operates to control the flow of electric power to the heating elements 52, and it may preferably be the control instrument known as the Reactrol manufactured by the General Electric Company. The control instrument 55 is connected to the heating elements 52 as shown.

Referring to the casting at the left hand of portion 42, there is a longitudinal slit 50, that is, an elongated opening through which ions of the vaporized material are withdrawn. Although not indicated in the drawings in order to maintain clarity in the showing of the inventive portions, actually the slit 50 is not formed directly in the casting 40 itself, but rather in a graphite assembly or insert, not shown, held in and heated by the casting. The vaporized material passes around a battle 46 and through a chimney in passing from the lower part 31 of casting 40 into the smaller upper part 42. Disposed at or adjacent to one end of the slit or elongated opening is a filamentary cathode 51, across the terminals of which a suitable voltage is impressed when the apparatus is in operation and as will presently be described. The

function of the cathode 51 in operation is to emit a stream of electrons into and along the slit 50, the electrons being collimated into a beam under the influence of the magnetic field previously described and serving to bombard the vapor before passing through the slit for I the purpose of ionizing the vapor.

To the left of the casting 40 is a member 56 which may preferably be made of carbon and which has therein a slot or elongated opening parallel to the slit 50 so that ions of the vapor emitted through the slit 50 can pass through the slit in member 56. The member 56 constitutes an electrode which serves as an accelerating electrode for positive ions emerging through the slit 50, and this electrode is maintained at a relatively high negative potential as will presently be described. It is supported from insulator 59.

The ions accelerated by the electrode 56 pass to the left through another slit 57 in a member 58 having a throat-like configuration and which also forms an electrode which may preferably be made of carbon. This electrode is also maintained at a relatively high negative potential but lower than the potential of the electrode 56. Positive ions after passing through the throat of member 58 pass into the liner structure 35, and then travel in arcs of a circle around through the liner to the receiving structure at the opposite side of the liner; the positive ions move in arcs of a circle in this manner under the influence of the magnetic field previously described, and the radii of the arcs depends on the mass-charge properties of the ionized particles.

There are two identical receiving chambers or collectors at the upper end of the liner structure 35, one of them being designated by the numeral 60. The receiving chamber 60 is in the form of a box having a shape which in cross section is shown in Fig. 1. The receiver or collector 60 may be adjusted laterally relative to the face plate by a stem 61 operating through linkages 62, and it may be adjusted in and out relative to the face plate by means of stem 63, the stems containing insulating sections schematically indicated at 64 and 65', respectively, and passing through the face plate 11 by means of vacuum sealing devices schematically indicated at 64 and 65, respectively. The collector 60 has pockets 71 and 72 therein which are so located as to receive certain components of the beam of ions which travels Lil) around through the liner 35. Diflerent components of the beam, that is, particles thereof having different mass-charge properties travel in circles of different radii as described above and come to a focus at different radial distances from their point of origin. Within the pockets 71 and 72 are electrodes 73 and 74 respectively which are insulated from the other portions of the collector structure so that the ion currents thereto may be individually metered. In operation of the apparatus the magnetic field is so adjusted and the collector 60 is so adjusted relative thereto that the isotopes which it is desired to collect impinge upon the desired receiving element. The desired isotopes may be gathered by removing the deposits which collect in the pockets 71 and 72.

The face plate 11 is grounded, as shown, as are the castings 40 and 40'. The liner 35, and the electrode 58 are maintained at a relatively high negative potential Vi by conductor 79 which is led into the interior of the tank through a conduit 76 which extends through the face plate 11 through a sealing insulator bushing 77. The electrode 56 is maintained at a higher negative potential V1+Vz by means of a conductor 78 which is led into the tank through a similar bushing 77 and a similar conduit 76. The electrodes 73 and 74 are connected to ammeters and 75, respectively, by means of conductors 80 and 81, respectively, and then to conductor 79 at potential V1. Conductors 86 and 81 are also led out of the tank through conduit 76 and bushing 77 along with conductor 79. A potential V3 is impressed across the terminals of the cathode 51 and a voltage V4 is impressed between the negative terminal of cathode 51 and ground, that is, the casting 40. This last potential sustains the are which is struck within slit 50 during operation.

Summarizing the operation of the apparatus as so far described, the operation is that the charge material in the bottle 43 is vaporized by the electric heating element 52, speaking of the casting 4t), and the vaporization is automatically controlled by the thermocouple in the well 53. The vapor passes into the upper portion 42 of the casting 40 where it is maintained in vapor state by the portion of heating element 52 associated therewith, and the vapor then passes out through the slit 50 where it is ionized by the stream of electrons from the cathode 51, an are being formed or struck in the slit 50 under the influence of voltage V4. Positive ions are attracted from the region of the slit by electrode 56 Jhich is maintained at a high negative potential and under the influence of electrode 58 the ions pass into the liner structure 35 and thence travel in arcs of a circle around to the collector 60, the radii of the arcs depending upon the mass-charge properties of the ionized particles. The collector 60 is adjusted as described so that the desired isotopes of the ionized material are received in the collector pockets.

Various of the parts of the mechanism within the tank 10 may be cooled as desired or necessary by a suitable cooling system and shielding may be provided at appropriate points to protect the mechanism from becoming coated as a result of being contacted by the vapor from the charge bottle, and thus protected against deterioration which may necessarily result from the process.

The geometry of the slit 50 relative to the other parts is quite critical, and during operation vaporized material may condense and collect on the defining edges of the slit or the slit may become otherwise fouled up or contaminated. It is necessary and desirable during operation that the slit be kept free from contaminating material insofar as possible. In order to accomplish this I provide a cleaner or scraper mechanism which may be manually operated for cleaning or scraping the defining edges of the slit and the material adjacent to the defining edges. The slit cleaner mechanism is shown diagrammatically in its operative position relative to the other parts in Fig. l, the cleaner mechanism being operated by a manually operative push rod or plunger 100 having a handle 101 outside of the face plate 11, the push rod 100 extending through a Wilson seal 102 into the interior of the tank 10. The mechanism of the slit cleaner apparatus is shown in enlarged perspective in Fig. 3 and reference is now made more particularly to Fig. 3 of the drawings. The slit cleaner mechanism embodies cleaning or scraping elements which move back and forth in the slits 50 and 50 and the cleaning or scraping elements are operated by a mechanism which causes them to move substantially in a straight line and which is disposed in a position between the castings and 40 as may be seen both on Figs. 1 and 3. Referring to Fig. 3, the cleaning or scraping device associated with slit in casting 40 comprises an element or block 105 which fits in or engages in the slit and is attached to a horizontal cleaner or scraper element or plate 1% which has a slanting surface at its forward edge as shown, and one surface of which engages the surface which defines the interior of the slit 50. Numeral ltli designates a second scraper element attached to the block 105 and one surface of which bears against the surface defining the exterior of the slit 50. In one end of the block 105 there is a transverse slot 11% and a longitudinal slot 111 and the block 105 is attached to a horizontal transverse crossarm 112 by means of an in wardly extending bracket or car 113 which engages a pin 114 extending transversely of the slot 111 and lying in slot 110. The cleaning or scraping element associated with the casting 40' is identical with that just described, the cleaning or scraping arrangements associated with the. castings 40 and 40' being equally spaced from the midpoint of the crossarm 112.

The midpoint of the crossarm 112 is attached to a lever 117, the inner end of which is pivoted as shown to a lever 118, the opposite end of which engages on a fixed pivot formed by a bolt 119 extending between brackets 120 and 121. The lever 117 extends through a guide slot parallel to the slits 5t) and 50, the guide slot 125 being in a structure 126 which may be built out from the castings 40 and 40 or which may be supported directly from the supporting structure 36 of Fig. 1. The frame structure 126 has an inner portion 127 and pivotally attached thereto by a bolt 128 is a triangle member or hell crank 12) which is spaced from the portion 127 by a bushing through which the bolt 128 extends. Movement of member 129 is limited by an adjustable stop screw 130. The bolt 12% extends through one corner of triangle 129; another corner of the triangle is pivoted to an intermediate point of lever 117 and the opposite corner of triangle 129 is pivotally attached as shown to a link 132, the opposi e end of which is pivotally attached to the push rod or operating stern which extends through the face plate 3.1 as previously described. The frame structure 126 also serves as a shield to prevent material from the tank from deposit'mg on the linkage arrangement and interfering with its free operation.

During operation of the apparatus of Fig. 1, the push rod or stem 100 may be reciprocated periodically at intervals from outside of the tank 10 for cleaning or scraping the slits 50 and 50' to free them of fouling or contaminating material. In the operation of the cleaning mechanism when the handle 101, that is the stem 1%, is pushed, the triangle 129 is rotated in a clockwise direction look-- ing at Fig. 3, that is, ink L32 pushes inwardly on the corner of triangle 129. This causes the lever 117 to rotate counterclockwise relative to the pivot at its lower end moving the crossarm 112 and its associated cleaning or scraping elements to the left looking at Fig. 3. As lever 117 rotates counterclockwise, its immediate point which is pivoted to a corner of triangle 129 is constrained to move in an arc of a circle, but its lower end moves outwardly with the lever 113 rotating in a clockwise direction looking at Fig. 3. The relationship of the centers, that is, the pivots and the lengths of the lever arms are such that as lever 117 is thus rotated counterclockwise its upper end moves to the left, looking at Fig. 3, in substantially a straight line so that the cleaning or scraping elements have a substantially straight line motion in the slits 50 and 50, the motion being guided by the guide slit 125 in which the lever 117 moves. When lever 117 reaches a position in which the two pins in lever 117 and the pin 128 are in line, continued counterclockwise movement of lever 117 will cause lever 113 to then move in a counterclockwise rather than a clockwise direction. When the stem 100 has been thus fully pushed in the cleaning or scraping elements in the slits 50 and 50 will have been moved to the opposite ends of the slits to move them back the handle 101 and the operating stem 1% are pulled out. This causes the parts to move in opposite directions to that just described. Reciprocating the operating stem 100 therefore causes the cleaning or scraping elements to move back and forth in a straight line in their respective slits. The block 105 associated with slit 5%) cleans and scrapes the side walls of the slit, the surface forming the interior of the slit is scraped by the blade member 106, and the surface forming the exterior of the slit is scraped by blade memher 107. The pivotal connection of crossarm 112 to the scraper elements permits the necessary amount of relative movement between crossarm 112 and the scraper elements.

The operating mechanism for producing straight line motion of the cleaning elements can be made very rugged so that the cleaning elements accurately move in a straight line without binding and without encumbering the immediate vicinity of the slits either with operating or guiding mechanism. Operation of the slit cleaning mechanism, therefore, does not impair the geometry of the slits in which they operate relative to other parts of the isotope separating apparatus.

From the foregoing, those skilled in the art will perceive that l have provided an improved device for cleaning the slits of the ion source or sources and maintaining them in efiicient operating condition. The arrangement provides an etficient means for operating slit cleaners, particularly since it is convenient that the operating stem should extend through the face plate 11 and the movement of the stem thus being perpendicular to the plane of the movement of the slit cleaning elements, it not being convenient to operate the slit cleaning elements from the side of the tank 10 due to the presence of the magnetic field producing means as shown in Fig. 2.

The foregoing disclosure is representative of a preferred form of my invention, and it is intended that it be interpreted in an illustrative rather than a limiting sense, it being intended that the scope of the invention be determined in accordance with the claims appended hereto.

I claim:

1. in apparatus of the character described, in combination, means forming an ion source, said source comprising a chamber having an elongated opening therein, means comprising an element movable in said opening for removing contaminating material from the defining edges thereof, said last means comprising mechanism for constraining said element to move in substantially a straight line in said opening, said mechanism including a lever a fixed pivot, a second lever pivoted to the first lever and a third lever on a fixed pivot and pivoted to said second lever so that when the third lever is rotated, the first and second levers rotate on their pivots with a portion of the second lever moving substantially in a straight line.

2. in apparatus of the character described, in combination, means forming a plurality of ion sources, each of said sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each or said openings for removing contaminating material from the defining edges thereof, means for operating said elements, said mechanism being operatively connected to all of the elements and arranged to constrain said elements to move in substantially a straight line in said openings, said mechanism comprising a lever on a fixed pivot, a second lever pivoted to the first lcver, and a third lever on a fixed pivot and pivoted to said second lever so that when the third lever is rotated, the first and second levers rotate on their pivots with a portion of the second lever moving substantially in a straight line.

3. In apparatus of the character described, in combination, means forming a plurality of ion sources, each of said sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each of said openings for removing contaminating material from the defining edges thereof, mechanism for operating said elements, said mechanism being operatively connected to all of the elements and arranged to constrain said elements to move in substantially a straight line in said openings, said mechanism being positioned in part between two of said ion sources and comprising an operating stem extending in a direction substantially perpendicular to the direction of movement of said elements.

4. In apparatus of the character described, in combination, means forming a plurality of ion sources, each of said sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each of said openings for removing contaminating material from the I.

defining edges thereof, mechanism for operating said elements, said mechanism being operatively connected to all of the elements and comprising a lever rotatable on a.pivot and lying in a plane parallel to said openings and between two of said sources, means for rotating said lever for constraining siad element to move in substantially a l straight line in said opening, said mechanism comprising means forming two levers mounted on fixed pivots so as to be rotatable thereabout, means forming a link pivoted to both of said levers, and means for rotating one of the levers so that the link rotates about its pivot on the other lever and the other lever also rotates, the link member having a portion which moves in substantially a straight line.

6. In apparatus of the character described, in combination, means forming a plurality of ion sources, each of asaid sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each of said openings for removing contaminating material from the defining edges thereof, mechanism for operating said elements, said mechanism being operatively connected to all of the elements and arranged to constrain said elements to move in substantially a straight line in said openings, said mechanism comprising two levers mounted on fixed pivots so as to be rotatable thereabout, means forming a link pivoted to both of said levers, and means for rotating one of the levers so that the link rotates about its pivot on the other lever and the other lever also rotates, the link member having a portion which moves in substantially a straight line, and said mechanism being disposed between two of said sources.

7. In apparatus of the character described, in combination, means forming an ion source, said source comprising a chamber having an elongated opening therein, means comprising an element movable in said opening for removing contaminating material from the defining edges thereof, said last means comprising mechanism for constraining said element to move in substantially a straight line in said opening, said mechanism including a lever on a fixed pivot, a second lever pivoted to the first lever and a third lever on a fixed pivot and pivoted to said second lever so that when the third lever is rotated, the first and second levers rotate on their pivots with a portion of the second lever moving substantially in a straight line, and means forming a guide for said second lever.

8. ln apparatus of the character described, in combination, means forming a plurality of ion sources, each of said sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each of said openings for removing contaminating material from the defining edges thereof, mechanism for operating said elements, said mechanism being operatively connected to all of the elements and arranged to constrain said elements to move in substantially a straight line in said openings, said mechanism comprising a lever on a fixed pivot a second lever pivoted to the first lever, and a third lever on a fixed pivot and pivoted to said second lever so that when the third lever is rotated, the first and second levers rotate on their pivots with a portion of the second lever moving substantially in a straight line, and means forming a guide for said second lever.

. In apparatus of the character described, in combination, means forming an ion source, said source comprising a chamber having an elongated opening therein, means comprising an element movable in said opening for removing contaminating material from the defining edges thereof, said last means comprising mechanism for constraining said element to move in substantially a straight line in said opening, said mechanism including a lever and a pivot which said lever is rotatable about as center, means for rotating said lever about said center, and for also moving said center in a manner whereby a portion of said lever moves in substantially a straight line, and means forming a guide for said lever.

10. In apparatus of the character described, in combination, means forming a plurality of ion sources, each of said sources comprising a chamber having an elongated opening therein, said elongated openings being parallel, means comprising an element movable in each of said openings for removing contaminating material from the defining edges thereof, mechanism for operating said elements, said mechanism being operatively connected to all of the elements and comprising a lever rotatable on a pivot and lying in a plane parallel to said openings and between two of said sources, means for rotating said lever on its pivot and for also moving said pivot in a manner to cause a portion of the lever to move in substantially a straight line, and means forming a guide for said lever.

No references cited. 

1. IN APPARATUS OF THE CHARACTER DESCRIBED, IN COMBINATION, MEANS FORMING AN ION SOURCE, SAID SOURCE COMPRISING A CHAMBER HAVING AN ELONGATED OPENING THEREIN, MEANS COMPRISING AN ELEMENT MOVABLE IN SAID OPENING FOR REMOVING CONTAMINATING MATERIAL FROM THE DEFINING EDGES THEREOF, SAID LAST MEANS COMPRISING MECHANISM FOR CONSTRAINING SAID ELEMENT TO MOVE IN SUBSTANTIALLY A STRAIGHT LINE IN SAID OPENING, SAID MECHANISM INCLUDING A LEVER ON A FIXED PIVOT, A SECOND LEVER PIVOTED TO THE FIRST LEVER AND A THIRD LEVER ON A FIXED PIVOT AND PIVOTED TO SAID SECOND LEVER SO THAN WHEN THE THIRD LEVER IS ROTATED, THE FIRST AND SECOND LEVERS ROTATED ON THE PIVOTS WITH A PORTION OF THE SECOND LEVER MOVING SUBSTANTIALLY IN A STRAIGT LINE. 